COIN-OR::LEMON - Graph Library

source: lemon-0.x/lemon/bfs.h @ 1516:4aeda8d11d5e

Last change on this file since 1516:4aeda8d11d5e was 1516:4aeda8d11d5e, checked in by Alpar Juttner, 14 years ago

processNextXyz() returns the processed object.

File size: 34.8 KB
Line 
1/* -*- C++ -*-
2 * lemon/bfs.h - Part of LEMON, a generic C++ optimization library
3 *
4 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
5 * (Egervary Research Group on Combinatorial Optimization, EGRES).
6 *
7 * Permission to use, modify and distribute this software is granted
8 * provided that this copyright notice appears in all copies. For
9 * precise terms see the accompanying LICENSE file.
10 *
11 * This software is provided "AS IS" with no warranty of any kind,
12 * express or implied, and with no claim as to its suitability for any
13 * purpose.
14 *
15 */
16
17#ifndef LEMON_BFS_H
18#define LEMON_BFS_H
19
20///\ingroup flowalgs
21///\file
22///\brief Bfs algorithm.
23
24#include <lemon/list_graph.h>
25#include <lemon/graph_utils.h>
26#include <lemon/invalid.h>
27#include <lemon/error.h>
28#include <lemon/maps.h>
29
30namespace lemon {
31
32
33 
34  ///Default traits class of Bfs class.
35
36  ///Default traits class of Bfs class.
37  ///\param GR Graph type.
38  template<class GR>
39  struct BfsDefaultTraits
40  {
41    ///The graph type the algorithm runs on.
42    typedef GR Graph;
43    ///\brief The type of the map that stores the last
44    ///edges of the shortest paths.
45    ///
46    ///The type of the map that stores the last
47    ///edges of the shortest paths.
48    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
49    ///
50    typedef typename Graph::template NodeMap<typename GR::Edge> PredMap;
51    ///Instantiates a PredMap.
52 
53    ///This function instantiates a \ref PredMap.
54    ///\param G is the graph, to which we would like to define the PredMap.
55    ///\todo The graph alone may be insufficient to initialize
56    static PredMap *createPredMap(const GR &G)
57    {
58      return new PredMap(G);
59    }
60//     ///\brief The type of the map that stores the last but one
61//     ///nodes of the shortest paths.
62//     ///
63//     ///The type of the map that stores the last but one
64//     ///nodes of the shortest paths.
65//     ///It must meet the \ref concept::WriteMap "WriteMap" concept.
66//     ///
67//     typedef NullMap<typename Graph::Node,typename Graph::Node> PredNodeMap;
68//     ///Instantiates a PredNodeMap.
69   
70//     ///This function instantiates a \ref PredNodeMap.
71//     ///\param G is the graph, to which
72//     ///we would like to define the \ref PredNodeMap
73//     static PredNodeMap *createPredNodeMap(const GR &G)
74//     {
75//       return new PredNodeMap();
76//     }
77
78    ///The type of the map that indicates which nodes are processed.
79 
80    ///The type of the map that indicates which nodes are processed.
81    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
82    ///\todo named parameter to set this type, function to read and write.
83    typedef NullMap<typename Graph::Node,bool> ProcessedMap;
84    ///Instantiates a ProcessedMap.
85 
86    ///This function instantiates a \ref ProcessedMap.
87    ///\param G is the graph, to which
88    ///we would like to define the \ref ProcessedMap
89    static ProcessedMap *createProcessedMap(const GR &)
90    {
91      return new ProcessedMap();
92    }
93    ///The type of the map that indicates which nodes are reached.
94 
95    ///The type of the map that indicates which nodes are reached.
96    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
97    ///\todo named parameter to set this type, function to read and write.
98    typedef typename Graph::template NodeMap<bool> ReachedMap;
99    ///Instantiates a ReachedMap.
100 
101    ///This function instantiates a \ref ReachedMap.
102    ///\param G is the graph, to which
103    ///we would like to define the \ref ReachedMap.
104    static ReachedMap *createReachedMap(const GR &G)
105    {
106      return new ReachedMap(G);
107    }
108    ///The type of the map that stores the dists of the nodes.
109 
110    ///The type of the map that stores the dists of the nodes.
111    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
112    ///
113    typedef typename Graph::template NodeMap<int> DistMap;
114    ///Instantiates a DistMap.
115 
116    ///This function instantiates a \ref DistMap.
117    ///\param G is the graph, to which we would like to define the \ref DistMap
118    static DistMap *createDistMap(const GR &G)
119    {
120      return new DistMap(G);
121    }
122  };
123 
124  ///%BFS algorithm class.
125 
126  ///\ingroup flowalgs
127  ///This class provides an efficient implementation of the %BFS algorithm.
128  ///
129  ///\param GR The graph type the algorithm runs on. The default value is
130  ///\ref ListGraph. The value of GR is not used directly by Bfs, it
131  ///is only passed to \ref BfsDefaultTraits.
132  ///\param TR Traits class to set various data types used by the algorithm.
133  ///The default traits class is
134  ///\ref BfsDefaultTraits "BfsDefaultTraits<GR>".
135  ///See \ref BfsDefaultTraits for the documentation of
136  ///a Bfs traits class.
137  ///
138  ///\author Alpar Juttner
139  ///\todo A compare object would be nice.
140
141#ifdef DOXYGEN
142  template <typename GR,
143            typename TR>
144#else
145  template <typename GR=ListGraph,
146            typename TR=BfsDefaultTraits<GR> >
147#endif
148  class Bfs {
149  public:
150    /**
151     * \brief \ref Exception for uninitialized parameters.
152     *
153     * This error represents problems in the initialization
154     * of the parameters of the algorithms.
155     */
156    class UninitializedParameter : public lemon::UninitializedParameter {
157    public:
158      virtual const char* exceptionName() const {
159        return "lemon::Bfs::UninitializedParameter";
160      }
161    };
162
163    typedef TR Traits;
164    ///The type of the underlying graph.
165    typedef typename TR::Graph Graph;
166    ///\e
167    typedef typename Graph::Node Node;
168    ///\e
169    typedef typename Graph::NodeIt NodeIt;
170    ///\e
171    typedef typename Graph::Edge Edge;
172    ///\e
173    typedef typename Graph::OutEdgeIt OutEdgeIt;
174   
175    ///\brief The type of the map that stores the last
176    ///edges of the shortest paths.
177    typedef typename TR::PredMap PredMap;
178//     ///\brief The type of the map that stores the last but one
179//     ///nodes of the shortest paths.
180//     typedef typename TR::PredNodeMap PredNodeMap;
181    ///The type of the map indicating which nodes are reached.
182    typedef typename TR::ReachedMap ReachedMap;
183    ///The type of the map indicating which nodes are processed.
184    typedef typename TR::ProcessedMap ProcessedMap;
185    ///The type of the map that stores the dists of the nodes.
186    typedef typename TR::DistMap DistMap;
187  private:
188    /// Pointer to the underlying graph.
189    const Graph *G;
190    ///Pointer to the map of predecessors edges.
191    PredMap *_pred;
192    ///Indicates if \ref _pred is locally allocated (\c true) or not.
193    bool local_pred;
194//     ///Pointer to the map of predecessors nodes.
195//     PredNodeMap *_predNode;
196//     ///Indicates if \ref _predNode is locally allocated (\c true) or not.
197//     bool local_predNode;
198    ///Pointer to the map of distances.
199    DistMap *_dist;
200    ///Indicates if \ref _dist is locally allocated (\c true) or not.
201    bool local_dist;
202    ///Pointer to the map of reached status of the nodes.
203    ReachedMap *_reached;
204    ///Indicates if \ref _reached is locally allocated (\c true) or not.
205    bool local_reached;
206    ///Pointer to the map of processed status of the nodes.
207    ProcessedMap *_processed;
208    ///Indicates if \ref _processed is locally allocated (\c true) or not.
209    bool local_processed;
210
211    std::vector<typename Graph::Node> _queue;
212    int _queue_head,_queue_tail,_queue_next_dist;
213    int _curr_dist;
214//     ///The source node of the last execution.
215//     Node source;
216
217    ///Creates the maps if necessary.
218   
219    ///\todo Error if \c G are \c NULL.
220    ///\todo Better memory allocation (instead of new).
221    void create_maps()
222    {
223      if(!_pred) {
224        local_pred = true;
225        _pred = Traits::createPredMap(*G);
226      }
227//       if(!_predNode) {
228//      local_predNode = true;
229//      _predNode = Traits::createPredNodeMap(*G);
230//       }
231      if(!_dist) {
232        local_dist = true;
233        _dist = Traits::createDistMap(*G);
234      }
235      if(!_reached) {
236        local_reached = true;
237        _reached = Traits::createReachedMap(*G);
238      }
239      if(!_processed) {
240        local_processed = true;
241        _processed = Traits::createProcessedMap(*G);
242      }
243    }
244   
245  public :
246 
247    ///\name Named template parameters
248
249    ///@{
250
251    template <class T>
252    struct DefPredMapTraits : public Traits {
253      typedef T PredMap;
254      static PredMap *createPredMap(const Graph &G)
255      {
256        throw UninitializedParameter();
257      }
258    };
259    ///\ref named-templ-param "Named parameter" for setting PredMap type
260
261    ///\ref named-templ-param "Named parameter" for setting PredMap type
262    ///
263    template <class T>
264    class DefPredMap : public Bfs< Graph,
265                                        DefPredMapTraits<T> > { };
266   
267//     template <class T>
268//     struct DefPredNodeMapTraits : public Traits {
269//       typedef T PredNodeMap;
270//       static PredNodeMap *createPredNodeMap(const Graph &G)
271//       {
272//      throw UninitializedParameter();
273//       }
274//     };
275//     ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
276
277//     ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
278//     ///
279//     template <class T>
280//     class DefPredNodeMap : public Bfs< Graph,
281//                                          LengthMap,
282//                                          DefPredNodeMapTraits<T> > { };
283   
284    template <class T>
285    struct DefDistMapTraits : public Traits {
286      typedef T DistMap;
287      static DistMap *createDistMap(const Graph &G)
288      {
289        throw UninitializedParameter();
290      }
291    };
292    ///\ref named-templ-param "Named parameter" for setting DistMap type
293
294    ///\ref named-templ-param "Named parameter" for setting DistMap type
295    ///
296    template <class T>
297    class DefDistMap : public Bfs< Graph,
298                                   DefDistMapTraits<T> > { };
299   
300    template <class T>
301    struct DefReachedMapTraits : public Traits {
302      typedef T ReachedMap;
303      static ReachedMap *createReachedMap(const Graph &G)
304      {
305        throw UninitializedParameter();
306      }
307    };
308    ///\ref named-templ-param "Named parameter" for setting ReachedMap type
309
310    ///\ref named-templ-param "Named parameter" for setting ReachedMap type
311    ///
312    template <class T>
313    class DefReachedMap : public Bfs< Graph,
314                                      DefReachedMapTraits<T> > { };
315   
316    struct DefGraphReachedMapTraits : public Traits {
317      typedef typename Graph::template NodeMap<bool> ReachedMap;
318      static ReachedMap *createReachedMap(const Graph &G)
319      {
320        return new ReachedMap(G);
321      }
322    };
323    template <class T>
324    struct DefProcessedMapTraits : public Traits {
325      typedef T ProcessedMap;
326      static ProcessedMap *createProcessedMap(const Graph &G)
327      {
328        throw UninitializedParameter();
329      }
330    };
331    ///\ref named-templ-param "Named parameter" for setting ProcessedMap type
332
333    ///\ref named-templ-param "Named parameter" for setting ProcessedMap type
334    ///
335    template <class T>
336    class DefProcessedMap : public Bfs< Graph,
337                                        DefProcessedMapTraits<T> > { };
338   
339    struct DefGraphProcessedMapTraits : public Traits {
340      typedef typename Graph::template NodeMap<bool> ProcessedMap;
341      static ProcessedMap *createProcessedMap(const Graph &G)
342      {
343        return new ProcessedMap(G);
344      }
345    };
346    ///\brief \ref named-templ-param "Named parameter"
347    ///for setting the ProcessedMap type to be Graph::NodeMap<bool>.
348    ///
349    ///\ref named-templ-param "Named parameter"
350    ///for setting the ProcessedMap type to be Graph::NodeMap<bool>.
351    ///If you don't set it explicitly, it will be automatically allocated.
352    template <class T>
353    class DefProcessedMapToBeDefaultMap :
354      public Bfs< Graph,
355                  DefGraphProcessedMapTraits> { };
356   
357    ///@}
358
359  public:     
360   
361    ///Constructor.
362   
363    ///\param _G the graph the algorithm will run on.
364    ///
365    Bfs(const Graph& _G) :
366      G(&_G),
367      _pred(NULL), local_pred(false),
368//       _predNode(NULL), local_predNode(false),
369      _dist(NULL), local_dist(false),
370      _reached(NULL), local_reached(false),
371      _processed(NULL), local_processed(false)
372    { }
373   
374    ///Destructor.
375    ~Bfs()
376    {
377      if(local_pred) delete _pred;
378//       if(local_predNode) delete _predNode;
379      if(local_dist) delete _dist;
380      if(local_reached) delete _reached;
381      if(local_processed) delete _processed;
382    }
383
384    ///Sets the map storing the predecessor edges.
385
386    ///Sets the map storing the predecessor edges.
387    ///If you don't use this function before calling \ref run(),
388    ///it will allocate one. The destructor deallocates this
389    ///automatically allocated map, of course.
390    ///\return <tt> (*this) </tt>
391    Bfs &predMap(PredMap &m)
392    {
393      if(local_pred) {
394        delete _pred;
395        local_pred=false;
396      }
397      _pred = &m;
398      return *this;
399    }
400
401    ///Sets the map indicating the reached nodes.
402
403    ///Sets the map indicating the reached nodes.
404    ///If you don't use this function before calling \ref run(),
405    ///it will allocate one. The destructor deallocates this
406    ///automatically allocated map, of course.
407    ///\return <tt> (*this) </tt>
408    Bfs &reachedMap(ReachedMap &m)
409    {
410      if(local_reached) {
411        delete _reached;
412        local_reached=false;
413      }
414      _reached = &m;
415      return *this;
416    }
417
418    ///Sets the map indicating the processed nodes.
419
420    ///Sets the map indicating the processed nodes.
421    ///If you don't use this function before calling \ref run(),
422    ///it will allocate one. The destructor deallocates this
423    ///automatically allocated map, of course.
424    ///\return <tt> (*this) </tt>
425    Bfs &processedMap(ProcessedMap &m)
426    {
427      if(local_processed) {
428        delete _processed;
429        local_processed=false;
430      }
431      _processed = &m;
432      return *this;
433    }
434
435//     ///Sets the map storing the predecessor nodes.
436
437//     ///Sets the map storing the predecessor nodes.
438//     ///If you don't use this function before calling \ref run(),
439//     ///it will allocate one. The destructor deallocates this
440//     ///automatically allocated map, of course.
441//     ///\return <tt> (*this) </tt>
442//     Bfs &predNodeMap(PredNodeMap &m)
443//     {
444//       if(local_predNode) {
445//      delete _predNode;
446//      local_predNode=false;
447//       }
448//       _predNode = &m;
449//       return *this;
450//     }
451
452    ///Sets the map storing the distances calculated by the algorithm.
453
454    ///Sets the map storing the distances calculated by the algorithm.
455    ///If you don't use this function before calling \ref run(),
456    ///it will allocate one. The destructor deallocates this
457    ///automatically allocated map, of course.
458    ///\return <tt> (*this) </tt>
459    Bfs &distMap(DistMap &m)
460    {
461      if(local_dist) {
462        delete _dist;
463        local_dist=false;
464      }
465      _dist = &m;
466      return *this;
467    }
468
469  public:
470    ///\name Execution control
471    ///The simplest way to execute the algorithm is to use
472    ///one of the member functions called \c run(...).
473    ///\n
474    ///If you need more control on the execution,
475    ///first you must call \ref init(), then you can add several source nodes
476    ///with \ref addSource().
477    ///Finally \ref start() will perform the actual path
478    ///computation.
479
480    ///@{
481
482    ///Initializes the internal data structures.
483
484    ///Initializes the internal data structures.
485    ///
486    void init()
487    {
488      create_maps();
489      _queue.resize(countNodes(*G));
490      _queue_head=_queue_tail=0;
491      _curr_dist=1;
492      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
493        _pred->set(u,INVALID);
494//      _predNode->set(u,INVALID);
495        _reached->set(u,false);
496        _processed->set(u,false);
497      }
498    }
499   
500    ///Adds a new source node.
501
502    ///Adds a new source node to the set of nodes to be processed.
503    ///
504    void addSource(Node s)
505    {
506      if(!(*_reached)[s])
507        {
508          _reached->set(s,true);
509          _pred->set(s,INVALID);
510          _dist->set(s,0);
511          _queue[_queue_head++]=s;
512          _queue_next_dist=_queue_head;
513        }
514    }
515   
516    ///Processes the next node.
517
518    ///Processes the next node.
519    ///
520    ///\return The processed node.
521    ///
522    ///\warning The queue must not be empty!
523    Node processNextNode()
524    {
525      if(_queue_tail==_queue_next_dist) {
526        _curr_dist++;
527        _queue_next_dist=_queue_head;
528      }
529      Node n=_queue[_queue_tail++];
530      _processed->set(n,true);
531      Node m;
532      for(OutEdgeIt e(*G,n);e!=INVALID;++e)
533        if(!(*_reached)[m=G->target(e)]) {
534          _queue[_queue_head++]=m;
535          _reached->set(m,true);
536          _pred->set(m,e);
537//        _pred_node->set(m,n);
538          _dist->set(m,_curr_dist);
539        }
540      return n;
541    }
542     
543    ///\brief Returns \c false if there are nodes
544    ///to be processed in the queue
545    ///
546    ///Returns \c false if there are nodes
547    ///to be processed in the queue
548    bool emptyQueue() { return _queue_tail==_queue_head; }
549    ///Returns the number of the nodes to be processed.
550   
551    ///Returns the number of the nodes to be processed in the queue.
552    ///
553    int queueSize() { return _queue_head-_queue_tail; }
554   
555    ///Executes the algorithm.
556
557    ///Executes the algorithm.
558    ///
559    ///\pre init() must be called and at least one node should be added
560    ///with addSource() before using this function.
561    ///
562    ///This method runs the %BFS algorithm from the root node(s)
563    ///in order to
564    ///compute the
565    ///shortest path to each node. The algorithm computes
566    ///- The shortest path tree.
567    ///- The distance of each node from the root(s).
568    ///
569    void start()
570    {
571      while ( !emptyQueue() ) processNextNode();
572    }
573   
574    ///Executes the algorithm until \c dest is reached.
575
576    ///Executes the algorithm until \c dest is reached.
577    ///
578    ///\pre init() must be called and at least one node should be added
579    ///with addSource() before using this function.
580    ///
581    ///This method runs the %BFS algorithm from the root node(s)
582    ///in order to
583    ///compute the
584    ///shortest path to \c dest. The algorithm computes
585    ///- The shortest path to \c  dest.
586    ///- The distance of \c dest from the root(s).
587    ///
588    void start(Node dest)
589    {
590      while ( !emptyQueue() && _queue[_queue_tail]!=dest ) processNextNode();
591    }
592   
593    ///Executes the algorithm until a condition is met.
594
595    ///Executes the algorithm until a condition is met.
596    ///
597    ///\pre init() must be called and at least one node should be added
598    ///with addSource() before using this function.
599    ///
600    ///\param nm must be a bool (or convertible) node map. The algorithm
601    ///will stop when it reaches a node \c v with <tt>nm[v]==true</tt>.
602    template<class NM>
603      void start(const NM &nm)
604      {
605        while ( !emptyQueue() && !nm[_queue[_queue_tail]] ) processNextNode();
606      }
607   
608    ///Runs %BFS algorithm from node \c s.
609   
610    ///This method runs the %BFS algorithm from a root node \c s
611    ///in order to
612    ///compute the
613    ///shortest path to each node. The algorithm computes
614    ///- The shortest path tree.
615    ///- The distance of each node from the root.
616    ///
617    ///\note d.run(s) is just a shortcut of the following code.
618    ///\code
619    ///  d.init();
620    ///  d.addSource(s);
621    ///  d.start();
622    ///\endcode
623    void run(Node s) {
624      init();
625      addSource(s);
626      start();
627    }
628   
629    ///Finds the shortest path between \c s and \c t.
630   
631    ///Finds the shortest path between \c s and \c t.
632    ///
633    ///\return The length of the shortest s---t path if there exists one,
634    ///0 otherwise.
635    ///\note Apart from the return value, d.run(s) is
636    ///just a shortcut of the following code.
637    ///\code
638    ///  d.init();
639    ///  d.addSource(s);
640    ///  d.start(t);
641    ///\endcode
642    int run(Node s,Node t) {
643      init();
644      addSource(s);
645      start(t);
646      return reached(t)?_curr_dist-1+(_queue_tail==_queue_next_dist):0;
647    }
648   
649    ///@}
650
651    ///\name Query Functions
652    ///The result of the %BFS algorithm can be obtained using these
653    ///functions.\n
654    ///Before the use of these functions,
655    ///either run() or start() must be called.
656   
657    ///@{
658
659    ///Copies the shortest path to \c t into \c p
660   
661    ///This function copies the shortest path to \c t into \c p.
662    ///If it \c \t is a source itself or unreachable, then it does not
663    ///alter \c p.
664    ///\todo Is it the right way to handle unreachable nodes?
665    ///\return Returns \c true if a path to \c t was actually copied to \c p,
666    ///\c false otherwise.
667    ///\sa DirPath
668    template<class P>
669    bool getPath(P &p,Node t)
670    {
671      if(reached(t)) {
672        p.clear();
673        typename P::Builder b(p);
674        for(b.setStartNode(t);pred(t)!=INVALID;t=predNode(t))
675          b.pushFront(pred(t));
676        b.commit();
677        return true;
678      }
679      return false;
680    }
681
682    ///The distance of a node from the root(s).
683
684    ///Returns the distance of a node from the root(s).
685    ///\pre \ref run() must be called before using this function.
686    ///\warning If node \c v in unreachable from the root(s) the return value
687    ///of this function is undefined.
688    int dist(Node v) const { return (*_dist)[v]; }
689
690    ///Returns the 'previous edge' of the shortest path tree.
691
692    ///For a node \c v it returns the 'previous edge'
693    ///of the shortest path tree,
694    ///i.e. it returns the last edge of a shortest path from the root(s) to \c
695    ///v. It is \ref INVALID
696    ///if \c v is unreachable from the root(s) or \c v is a root. The
697    ///shortest path tree used here is equal to the shortest path tree used in
698    ///\ref predNode(Node v).
699    ///\pre Either \ref run() or \ref start() must be called before using
700    ///this function.
701    ///\todo predEdge could be a better name.
702    Edge pred(Node v) const { return (*_pred)[v];}
703
704    ///Returns the 'previous node' of the shortest path tree.
705
706    ///For a node \c v it returns the 'previous node'
707    ///of the shortest path tree,
708    ///i.e. it returns the last but one node from a shortest path from the
709    ///root(a) to \c /v.
710    ///It is INVALID if \c v is unreachable from the root(s) or
711    ///if \c v itself a root.
712    ///The shortest path tree used here is equal to the shortest path
713    ///tree used in \ref pred(Node v).
714    ///\pre Either \ref run() or \ref start() must be called before
715    ///using this function.
716    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
717                                  G->source((*_pred)[v]); }
718   
719    ///Returns a reference to the NodeMap of distances.
720
721    ///Returns a reference to the NodeMap of distances.
722    ///\pre Either \ref run() or \ref init() must
723    ///be called before using this function.
724    const DistMap &distMap() const { return *_dist;}
725 
726    ///Returns a reference to the shortest path tree map.
727
728    ///Returns a reference to the NodeMap of the edges of the
729    ///shortest path tree.
730    ///\pre Either \ref run() or \ref init()
731    ///must be called before using this function.
732    const PredMap &predMap() const { return *_pred;}
733 
734//     ///Returns a reference to the map of nodes of shortest paths.
735
736//     ///Returns a reference to the NodeMap of the last but one nodes of the
737//     ///shortest path tree.
738//     ///\pre \ref run() must be called before using this function.
739//     const PredNodeMap &predNodeMap() const { return *_predNode;}
740
741    ///Checks if a node is reachable from the root.
742
743    ///Returns \c true if \c v is reachable from the root.
744    ///\warning The source nodes are indicated as unreached.
745    ///\pre Either \ref run() or \ref start()
746    ///must be called before using this function.
747    ///
748    bool reached(Node v) { return (*_reached)[v]; }
749   
750    ///@}
751  };
752
753  ///Default traits class of Bfs function.
754
755  ///Default traits class of Bfs function.
756  ///\param GR Graph type.
757  template<class GR>
758  struct BfsWizardDefaultTraits
759  {
760    ///The graph type the algorithm runs on.
761    typedef GR Graph;
762    ///\brief The type of the map that stores the last
763    ///edges of the shortest paths.
764    ///
765    ///The type of the map that stores the last
766    ///edges of the shortest paths.
767    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
768    ///
769    typedef NullMap<typename Graph::Node,typename GR::Edge> PredMap;
770    ///Instantiates a PredMap.
771 
772    ///This function instantiates a \ref PredMap.
773    ///\param G is the graph, to which we would like to define the PredMap.
774    ///\todo The graph alone may be insufficient to initialize
775    static PredMap *createPredMap(const GR &)
776    {
777      return new PredMap();
778    }
779//     ///\brief The type of the map that stores the last but one
780//     ///nodes of the shortest paths.
781//     ///
782//     ///The type of the map that stores the last but one
783//     ///nodes of the shortest paths.
784//     ///It must meet the \ref concept::WriteMap "WriteMap" concept.
785//     ///
786//     typedef NullMap<typename Graph::Node,typename Graph::Node> PredNodeMap;
787//     ///Instantiates a PredNodeMap.
788   
789//     ///This function instantiates a \ref PredNodeMap.
790//     ///\param G is the graph, to which
791//     ///we would like to define the \ref PredNodeMap
792//     static PredNodeMap *createPredNodeMap(const GR &G)
793//     {
794//       return new PredNodeMap();
795//     }
796
797    ///The type of the map that indicates which nodes are processed.
798 
799    ///The type of the map that indicates which nodes are processed.
800    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
801    ///\todo named parameter to set this type, function to read and write.
802    typedef NullMap<typename Graph::Node,bool> ProcessedMap;
803    ///Instantiates a ProcessedMap.
804 
805    ///This function instantiates a \ref ProcessedMap.
806    ///\param G is the graph, to which
807    ///we would like to define the \ref ProcessedMap
808    static ProcessedMap *createProcessedMap(const GR &)
809    {
810      return new ProcessedMap();
811    }
812    ///The type of the map that indicates which nodes are reached.
813 
814    ///The type of the map that indicates which nodes are reached.
815    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
816    ///\todo named parameter to set this type, function to read and write.
817    typedef typename Graph::template NodeMap<bool> ReachedMap;
818    ///Instantiates a ReachedMap.
819 
820    ///This function instantiates a \ref ReachedMap.
821    ///\param G is the graph, to which
822    ///we would like to define the \ref ReachedMap.
823    static ReachedMap *createReachedMap(const GR &G)
824    {
825      return new ReachedMap(G);
826    }
827    ///The type of the map that stores the dists of the nodes.
828 
829    ///The type of the map that stores the dists of the nodes.
830    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
831    ///
832    typedef NullMap<typename Graph::Node,int> DistMap;
833    ///Instantiates a DistMap.
834 
835    ///This function instantiates a \ref DistMap.
836    ///\param G is the graph, to which we would like to define the \ref DistMap
837    static DistMap *createDistMap(const GR &)
838    {
839      return new DistMap();
840    }
841  };
842 
843  /// Default traits used by \ref BfsWizard
844
845  /// To make it easier to use Bfs algorithm
846  ///we have created a wizard class.
847  /// This \ref BfsWizard class needs default traits,
848  ///as well as the \ref Bfs class.
849  /// The \ref BfsWizardBase is a class to be the default traits of the
850  /// \ref BfsWizard class.
851  template<class GR>
852  class BfsWizardBase : public BfsWizardDefaultTraits<GR>
853  {
854
855    typedef BfsWizardDefaultTraits<GR> Base;
856  protected:
857    /// Type of the nodes in the graph.
858    typedef typename Base::Graph::Node Node;
859
860    /// Pointer to the underlying graph.
861    void *_g;
862    ///Pointer to the map of reached nodes.
863    void *_reached;
864    ///Pointer to the map of processed nodes.
865    void *_processed;
866    ///Pointer to the map of predecessors edges.
867    void *_pred;
868//     ///Pointer to the map of predecessors nodes.
869//     void *_predNode;
870    ///Pointer to the map of distances.
871    void *_dist;
872    ///Pointer to the source node.
873    Node _source;
874   
875    public:
876    /// Constructor.
877   
878    /// This constructor does not require parameters, therefore it initiates
879    /// all of the attributes to default values (0, INVALID).
880    BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
881//                         _predNode(0),
882                           _dist(0), _source(INVALID) {}
883
884    /// Constructor.
885   
886    /// This constructor requires some parameters,
887    /// listed in the parameters list.
888    /// Others are initiated to 0.
889    /// \param g is the initial value of  \ref _g
890    /// \param s is the initial value of  \ref _source
891    BfsWizardBase(const GR &g, Node s=INVALID) :
892      _g((void *)&g), _reached(0), _processed(0), _pred(0),
893//       _predNode(0),
894      _dist(0), _source(s) {}
895
896  };
897 
898  /// A class to make the usage of Bfs algorithm easier
899
900  /// This class is created to make it easier to use Bfs algorithm.
901  /// It uses the functions and features of the plain \ref Bfs,
902  /// but it is much simpler to use it.
903  ///
904  /// Simplicity means that the way to change the types defined
905  /// in the traits class is based on functions that returns the new class
906  /// and not on templatable built-in classes.
907  /// When using the plain \ref Bfs
908  /// the new class with the modified type comes from
909  /// the original class by using the ::
910  /// operator. In the case of \ref BfsWizard only
911  /// a function have to be called and it will
912  /// return the needed class.
913  ///
914  /// It does not have own \ref run method. When its \ref run method is called
915  /// it initiates a plain \ref Bfs class, and calls the \ref Bfs::run
916  /// method of it.
917  template<class TR>
918  class BfsWizard : public TR
919  {
920    typedef TR Base;
921
922    ///The type of the underlying graph.
923    typedef typename TR::Graph Graph;
924    //\e
925    typedef typename Graph::Node Node;
926    //\e
927    typedef typename Graph::NodeIt NodeIt;
928    //\e
929    typedef typename Graph::Edge Edge;
930    //\e
931    typedef typename Graph::OutEdgeIt OutEdgeIt;
932   
933    ///\brief The type of the map that stores
934    ///the reached nodes
935    typedef typename TR::ReachedMap ReachedMap;
936    ///\brief The type of the map that stores
937    ///the processed nodes
938    typedef typename TR::ProcessedMap ProcessedMap;
939    ///\brief The type of the map that stores the last
940    ///edges of the shortest paths.
941    typedef typename TR::PredMap PredMap;
942//     ///\brief The type of the map that stores the last but one
943//     ///nodes of the shortest paths.
944//     typedef typename TR::PredNodeMap PredNodeMap;
945    ///The type of the map that stores the dists of the nodes.
946    typedef typename TR::DistMap DistMap;
947
948public:
949    /// Constructor.
950    BfsWizard() : TR() {}
951
952    /// Constructor that requires parameters.
953
954    /// Constructor that requires parameters.
955    /// These parameters will be the default values for the traits class.
956    BfsWizard(const Graph &g, Node s=INVALID) :
957      TR(g,s) {}
958
959    ///Copy constructor
960    BfsWizard(const TR &b) : TR(b) {}
961
962    ~BfsWizard() {}
963
964    ///Runs Bfs algorithm from a given node.
965   
966    ///Runs Bfs algorithm from a given node.
967    ///The node can be given by the \ref source function.
968    void run()
969    {
970      if(Base::_source==INVALID) throw UninitializedParameter();
971      Bfs<Graph,TR> alg(*(Graph*)Base::_g);
972      if(Base::_reached)
973        alg.reachedMap(*(ReachedMap*)Base::_reached);
974      if(Base::_processed) alg.processedMap(*(ProcessedMap*)Base::_processed);
975      if(Base::_pred) alg.predMap(*(PredMap*)Base::_pred);
976//       if(Base::_predNode) alg.predNodeMap(*(PredNodeMap*)Base::_predNode);
977      if(Base::_dist) alg.distMap(*(DistMap*)Base::_dist);
978      alg.run(Base::_source);
979    }
980
981    ///Runs Bfs algorithm from the given node.
982
983    ///Runs Bfs algorithm from the given node.
984    ///\param s is the given source.
985    void run(Node s)
986    {
987      Base::_source=s;
988      run();
989    }
990
991    template<class T>
992    struct DefPredMapBase : public Base {
993      typedef T PredMap;
994      static PredMap *createPredMap(const Graph &) { return 0; };
995      DefPredMapBase(const TR &b) : TR(b) {}
996    };
997   
998    ///\brief \ref named-templ-param "Named parameter"
999    ///function for setting PredMap
1000    ///
1001    /// \ref named-templ-param "Named parameter"
1002    ///function for setting PredMap
1003    ///
1004    template<class T>
1005    BfsWizard<DefPredMapBase<T> > predMap(const T &t)
1006    {
1007      Base::_pred=(void *)&t;
1008      return BfsWizard<DefPredMapBase<T> >(*this);
1009    }
1010   
1011 
1012    template<class T>
1013    struct DefReachedMapBase : public Base {
1014      typedef T ReachedMap;
1015      static ReachedMap *createReachedMap(const Graph &) { return 0; };
1016      DefReachedMapBase(const TR &b) : TR(b) {}
1017    };
1018   
1019    ///\brief \ref named-templ-param "Named parameter"
1020    ///function for setting ReachedMap
1021    ///
1022    /// \ref named-templ-param "Named parameter"
1023    ///function for setting ReachedMap
1024    ///
1025    template<class T>
1026    BfsWizard<DefReachedMapBase<T> > reachedMap(const T &t)
1027    {
1028      Base::_pred=(void *)&t;
1029      return BfsWizard<DefReachedMapBase<T> >(*this);
1030    }
1031   
1032
1033    template<class T>
1034    struct DefProcessedMapBase : public Base {
1035      typedef T ProcessedMap;
1036      static ProcessedMap *createProcessedMap(const Graph &) { return 0; };
1037      DefProcessedMapBase(const TR &b) : TR(b) {}
1038    };
1039   
1040    ///\brief \ref named-templ-param "Named parameter"
1041    ///function for setting ProcessedMap
1042    ///
1043    /// \ref named-templ-param "Named parameter"
1044    ///function for setting ProcessedMap
1045    ///
1046    template<class T>
1047    BfsWizard<DefProcessedMapBase<T> > processedMap(const T &t)
1048    {
1049      Base::_pred=(void *)&t;
1050      return BfsWizard<DefProcessedMapBase<T> >(*this);
1051    }
1052   
1053
1054//     template<class T>
1055//     struct DefPredNodeMapBase : public Base {
1056//       typedef T PredNodeMap;
1057//       static PredNodeMap *createPredNodeMap(const Graph &G) { return 0; };
1058//       DefPredNodeMapBase(const TR &b) : TR(b) {}
1059//     };
1060   
1061//     ///\brief \ref named-templ-param "Named parameter"
1062//     ///function for setting PredNodeMap type
1063//     ///
1064//     /// \ref named-templ-param "Named parameter"
1065//     ///function for setting PredNodeMap type
1066//     ///
1067//     template<class T>
1068//     BfsWizard<DefPredNodeMapBase<T> > predNodeMap(const T &t)
1069//     {
1070//       Base::_predNode=(void *)&t;
1071//       return BfsWizard<DefPredNodeMapBase<T> >(*this);
1072//     }
1073   
1074    template<class T>
1075    struct DefDistMapBase : public Base {
1076      typedef T DistMap;
1077      static DistMap *createDistMap(const Graph &) { return 0; };
1078      DefDistMapBase(const TR &b) : TR(b) {}
1079    };
1080   
1081    ///\brief \ref named-templ-param "Named parameter"
1082    ///function for setting DistMap type
1083    ///
1084    /// \ref named-templ-param "Named parameter"
1085    ///function for setting DistMap type
1086    ///
1087    template<class T>
1088    BfsWizard<DefDistMapBase<T> > distMap(const T &t)
1089    {
1090      Base::_dist=(void *)&t;
1091      return BfsWizard<DefDistMapBase<T> >(*this);
1092    }
1093   
1094    /// Sets the source node, from which the Bfs algorithm runs.
1095
1096    /// Sets the source node, from which the Bfs algorithm runs.
1097    /// \param s is the source node.
1098    BfsWizard<TR> &source(Node s)
1099    {
1100      Base::_source=s;
1101      return *this;
1102    }
1103   
1104  };
1105 
1106  ///Function type interface for Bfs algorithm.
1107
1108  /// \ingroup flowalgs
1109  ///Function type interface for Bfs algorithm.
1110  ///
1111  ///This function also has several
1112  ///\ref named-templ-func-param "named parameters",
1113  ///they are declared as the members of class \ref BfsWizard.
1114  ///The following
1115  ///example shows how to use these parameters.
1116  ///\code
1117  ///  bfs(g,source).predMap(preds).run();
1118  ///\endcode
1119  ///\warning Don't forget to put the \ref BfsWizard::run() "run()"
1120  ///to the end of the parameter list.
1121  ///\sa BfsWizard
1122  ///\sa Bfs
1123  template<class GR>
1124  BfsWizard<BfsWizardBase<GR> >
1125  bfs(const GR &g,typename GR::Node s=INVALID)
1126  {
1127    return BfsWizard<BfsWizardBase<GR> >(g,s);
1128  }
1129
1130} //END OF NAMESPACE LEMON
1131
1132#endif
1133
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